The present invention relates generally to data processors, and more specifically to a data transfer controller for a data processor of the type which is provided with an extended buffer memory in addition to the main memory.
In a supercomputer involving large scale scientific calculations, it is sometimes impossible to store all the necessary data simultaneously in the main memory. As a result, a large capacity extended buffer memory has been additionally provided to permit high speed data transfer. If a fault is detected in the extended buffer memory during a data transfer mode, the controlling program is notified of this fact to cancel instructions which are being performed or have been put in a queue waiting to be executed. The controlling program segregates the extended buffer memory from the system to fix the fault, and after recovery the extended buffer memory is integrated again with the system.
However, due to the cancellation of instructions, all flip-flops which are set for the cancelled instructions must be cleared and reset with the next instructions. This adds to significant complexity to the control algorithm and results in an increase in the amount of hardware.